Tuesday, July 31, 2012

GEM Ensembles Landfall Major Hurricane on US Soil


Several members of the Canadian's GEM model are landfalling a major hurricane on US soil on August 9th as Invest 99 begins to gather itself in the Eastern Atlantic.

Three of the members shown above have a strong low pressure system hitting the Northeast and Mid Atlantic regions on the 9th, which would have potentially devastating effects should there be significant rainfall that may overwhelm sewer systems in the area. Worth mentioning is member 2 of the GEM Ensembles, which has a 944mb major hurricane hitting the Northeast, which would just be catastrophic. Two other members also hit Florida as a strong low pressure system, both of which are in the 980mb realm, considered a fair hurricane.

The potential that this will actually happen is next to nothing. The GEM is known for overdoing things, and the atmosphere will not nearly be able to handle a system of such power, leaving that solution out of any reasonable possibility of a landfall.

This is still very much worth watching. While the eventual track and strength of the system may not be the solutions shown above, they still bear watching.

Andrew

Positive PNA May Save Midwest Winter Yet

http://origin.cpc.ncep.noaa.gov/products/people/wwang/cfsv2fcst/imagesInd3/glbz200SeaInd4.gif
The CFS v2 is showing a ridge of high pressure over the West Coast, seen by the arcing shape of the lines over the western part of the nation on this map of 200mb anomalies. Of additional interest is the depression of lines over the Southeast.

So, what does this all mean?

The ridge in the west and increased jet stream action in the southeast are characteristic of a positive PNA, which is made up of a high pressure system in the western part of the nation, as well as a storm track becoming enhanced over the Plains and Midwest into the East Coast. The graphic of a positive PNA can be seen below.

http://www.nc-climate.ncsu.edu/edu/k12/PNA/body
A positive PNA was actually a key player in creating the Chicago Blizzard in 2011.

Of additional interest is that this potential positive PNA may team up with the incoming El Nino. The El Nino is shown on the first image as an enhanced area of 200mb anomalies over the Southeast. This enhancement is characteristic of the sub-tropical jet stream, which is enhanced in an El Nino and gives the Northeast strong Nor'easters.

All of that said, if this were to turn out, we could have a 'saved' winter for the Midwest and Ohio Valley thanks to the positive PNA. However, I cannot confirm that this is in fact a positive PNA. This is just what it appears as, and could very well change in the future.

That's enough winter posts for today.

Andrew

Westward Propagation of El Nino Beginning

Westward propagation of warm water anomalies in the ENSO monitoring area has begun, as seen in this animation link.

Weekly sea surface temperature anomalies show a movement westward of waters with temperatures anywhere from 1-1.5 degrees above normal in the image above. This westward movement enhances the potential for a central-based or west-based El Nino this winter, both of which would be better for an East US snowy winter than an east based Nino.

It will take some time to see if this propagation continues, but this is an encouraging sign for those wanting snow on the East Coast and Northeast regions.

Andrew

2008-10, 2011-12 Southern Oscillation Index Values Similar

Values between the 2008-2010 Southern Oscillation Index (SOI) readings and 2011-present SOI readings are eerily similar. The 2008-2010 SOI values are above. The period begins with an SOI indicative of a La Nina, with readings between 10 and 25 in the early months of 2008. This was followed by a significant drop off into negative territory and a rebound into positive territory. The following year included continuous plummeting values of the SOI, with a reading approaching negative 20 in early 2010.

Now let's look at 2011-present SOI readings.

The timeframe in question began similarly to 2008, with an elevated La Nina-status SOI. An abrupt falling of the SOI followed, and a rebound into La Nina territory. Does this look familiar? If you're thinking of the graph above and its similarities, then you are making the right connection.

If we use 2008-2012 to forecast for the next year or two as the two graphs are markedly similar, one would expect an increasing El Nino, rebounding into La Nina as we move into 2013. I personally do not want to forecast that far out just out of confidence issues, but I find it very interesting that these two graphs are so much alike, only enhancing the general 2009-10 analog for the upcoming winter.

Andrew

Invest 99 Becomes More Organized

Invest 99 continues to strengthen and become more organized as it makes its way westward towards the Caribbean.

Latest analysis of Invest 99 shows several clusters of strong thunderstorms, with the biggest cluster containing the center of circulation and main component of the invest. The center of Invest 99 does not have a defined circulation, and at this time appears only as an area with a cluster of strong thunderstorms.
Invest 99 is in a difficult spot, warding off expanses of dry air to the north and west of itself. This dry air to the west may pose development problems, but the GFS ensembles say otherwise.

The 12z run of the GFS Ensembles, or GEFS, shows 1008 millibar lines as well as 1048 millibar lines. The ensembles show that the invest may move into the Caribbean at 1008 millibar strength. Given, other ensemble members are likely stronger with the system while others are weaker, but for now this is what seems to be a good level to track this invest.

Andrew

Monday, July 30, 2012

Active Fall Pattern Emerging

An active pattern looks to be in store this fall if the CFS is to verify.

The 500mb forecast for October shows a depression of height lines on the West Coast which has been outlined in blue. This depression is characteristic of a storm track pushing through the West Coast and through the Southwest. This track is traditional for what can become severe weather outbreaks in the Southern Plains. The area outlined in red is for where this pattern could produce an active weather pattern going into fall.
This pattern could be temporary, as the CFS does not predict this depression on the West Coast going into the rest of fall and early winter months. However, I find this to be an interesting development, as this would essentially break down the ridge that has been spreading record-breaking heat across much of the nation.

Andrew

Organized Severe Weather Potential in Midwest in Early August

There is a severe weather threat over the Upper Midwest and Midwest into the western Great Lakes in early August, particularly on Saturday, August 4.

Prognosis
A disturbance is forecast to press through the US/Canada border around Minnesota on August 4. As the disturbance enters the region, mid and lower level winds are forecast to increase in response to friction between the disturbance and a mega-ridge in the Southern US.
As the system deepens over the Upper Midwest, 850mb winds are progged to increase over the northern Plains into the Lower Great Lakes as the atmosphere encourages organized severe weather to form. The presence of instability worthy of organized severe weather looks to be significant, with instability values on the order of over 5500 j/kg in the Lower Great Lakes region, with roughly 2000-4000 j/kg in the Upper Midwest, where 850mb winds may be stronger than those to the south, thus encouraging more organized severe weather potential.
I find it likely that an organized severe weather threat will pan out in the afternoon and evening of August 4, with the Upper Midwest likely containing organized severe weather, and the Midwest dealing with a more volatile atmosphere but with less lower level winds that would specialize in severe weather. Despite the lack of favorable winds, there remains an amount of winds that I find it possible for an organized severe weather threat to develop in the Lower Great Lakes as well.

Andrew

Invest 99 Forms; Development in Caribbean Possible

Invest 99 has formed off of Africa with little evidence of circulation but an abundance of showers and storms.

Satellite imagery indicates that Invest 99 is composed of several clusters of showers and thunderstorms, with what could be a weak center of circulation in the middle of the image shown above. However, no significant circulation is evident, nor any enhanced convection around the weak circulation. Thus, the invest appears weak at this time.

However, the GFS Ensembles (GEFS) are forecasting this invest to trend westward and into the Caribbean, shown as the circles in the above image. This image shows 1008 and 1048 isobar markings, meaning that this invest could stay in fairly weak territory. Despite this, I find that the Caribbean may be supportive enough for development should the MJO race around to Phases 8-2 in the next 5 or 7 days in order to make a 'perfect storm' of development potential. Whether that happens remains to be seen.

Andrew

Sunday, July 29, 2012

ECMWF Ensembles' Forecast On Par With Expected Winter Conditions

ECHAMA Precipitation Rate Anomaly

ECHAMF Temperature Forecast Anomaly

The ECMWF Ensemble forecasts for December-January-February (DJF) appears to be the most in line with having a reasonable forecast, over other forecast members of the NMME association. Here's why I chose the ECHAMA and ECHAMF, members of the ECMWF squad.

Ridge over Gulf of Alaska (GOA)
There were some models showing warmer than normal temperatures over Alaska, signifying a high pressure over the area. However, after viewing temperature forecasts on the same members, those members showed above normal precipitation for Alaska, not in line with a high pressure over the Gulf of Alaska. Thus, those members were ruled out.

Ridge over GOA + Cool East US
A ridge over the Gulf of Alaska will lead to cooler than normal conditions over the eastern US. Similarly, a low pressure system over the Gulf of Alaska will bring warmer than normal conditions over the eastern US, as was seen last winter. However, despite a warm Gulf of Alaska, a few members showed a warmer than normal Eastern US, disqualifying their reason into their forecasts.

Wet Conditions over the Eastern US
Due to an incoming El Nino, wetter than normal conditions are expected over the Gulf of Mexico coast as well as the East Coast. One or two members displayed below normal precipitation anomalies over the mentioned areas, practically ignoring the El Nino that will be present come winter-time.

All of that said, I find it probable that if a forecast of the NMME members were to verify, it would be the ECHAMA and ECHAMF forecast maps charted above as described above.

Andrew

ECMWF Digs Strong Disturbance; Accompanying Severe Threat Possible

The ECMWF continues to show the prospect for a potential severe weather event in the first week of August, projecting a deepening disturbance over the western Great Lakes area.

This ECMWF solution seems pretty solid. A strong high pressure ridge remains over much of the southwestern US, and this does not look to go away anytime soon. If anything, expansion eastward seems probable. At the same time, a negative NAO currently in place is likely to persist into August, bringing the likelihood of a disturbance swinging down into the Great Lakes/Northeast regions in accordance with the buckling of the jet stream as is typical in a negative NAO.

If such deepening of a disturbance were to occur, an area of instability would be potent over the Midwest as a cold front attached to the back end of the disturbance would likely swing south and may ignite some strong to severe storms across the Midwest area. However, let's not jump to that conclusion just yet. It remains unknown where any cold front may set up, and if any instability could fuel any thunderstorms. Further analysis of the ECMWF at the same forecast hour reveals lower level winds in place over the Midwest, signaling a favorable thunderstorm atmosphere. However, jet stream winds look to be displaced to the east, which would diminish a tornado threat.

Andrew

Atlantic Development May Increase Soon

Development potential in the Atlantic Ocean may increase in due time as the Madden-Julian Oscillation (MJO) cycles towards Phases 8 and 1. These phases are conductive to development as convection is enhanced over the region.
The model solutions still vary, with the ECMWF forecasting a Phase 1 or 2 situation, which wouldn't be too conductive for tropical cyclone development.

Andrew

Atlantic Development May Increase Soon

Development potential in the Atlantic Ocean may increase in due time as the Madden-Julian Oscillation (MJO) cycles towards Phases 8 and 1. These phases are conductive to development as convection is enhanced over the region.
The model solutions still vary, with the ECMWF forecasting a Phase 1 or 2 situation, which wouldn't be too conductive for tropical cyclone development.

Andrew

Negative NAO Shows No Signs of Letting Up

Sea Surface Temperatures (SST) continue to indicate that the negative NAO that has been in place for well over a month now will continue to stand its ground for at least the next couple weeks.
SST's show a large region of warmer than normal temperature anomalies in the waters surrounding Greenland and as far south as Nova Scotia, Canada. This large warm water anomaly gives a strong indication that a negative NAO is present in the area, with no signal that it is to let up soon.

The NAO ensemble forecasts show a continued negative NAO engagement through the next several days, further enhancing the potential for a disturbance to sweep down from Canada and strike the Northeast with potential severe implications. Whether that comes to fruition remains to be seen.
I feel that the ensemble forecasts are not in the most accurate of realms- yesterday they were displaying a trend to a positive NAO phase, whereas today the ensembles have shifted to a more negative phase. That said, I don't have too much confidence in the ensembles at this time, but I do believe that the forecast listed above is more likely to pan out than a positive NAO.

Of additional interest surrounding the NAO is what the stratosphere is saying in response. In recent weeks, the stratosphere has been warming to normal levels, while it had been near record low temperatures before the negative NAO stepped into the picture.
Because the stratosphere remains at near normal levels rather than cooler than normal, I believe that the negative NAO will remain in place for a while to come.

Is it possible for the negative NAO to stick around into winter? It's possible, but prolonged patterns are like trying to treat diseases with one type of medicine- the more you use that one type, the more potential the disease has to find a way around it and break down the medicine's effectiveness. In this case, the atmosphere could find a way to break through the negative NAO and intense high pressure regimes before winter. Accurate forecasting on those regimes, however, is not warranted at this time.

Andrew

Saturday, July 28, 2012

Tropics Quiet; Disturbance Moving Off Africa

Regional Satellite Analysis

Surface Analysis
The tropics are fairly quiet this evening, with no large areas of convection across the board, other than a cluster moving off Africa, which will be discussed later.

Caribbean
The Caribbean is quiet at the moment. Surface analysis indicates two tropical waves moving into the region, but neither are posing substantial shower and thunderstorm activity and thus are not favored for any development in the next while.

Gulf of Mexico
Showers and thunderstorms are propagating on the Gulf coast, but little significant storm activity exists in the Gulf of Mexico. These coastal showers and storms are fueled by the presence of a pair of troughs in the region, feeding off the humidity and warm air to produce showers and thunderstorms.

Eastern Atlantic
There is a disturbance moving off of Africa and is producing a large region of showers and storms. Surface analysis shows these storms developing along the monsoonal trough and in the presence of a low pressure area. Shearing, shown below, indicates that significant development in the next day or two does not seem too likely.

Shearing in mid levels


Andrew

Images obtained from:
-Shearing image: CIMSS
-Surface Analysis: OPC
-Regional Satellite: NHC

Severe Weather Threat May Accompany Early August Disturbance

The 12z ECMWF is projecting a disturbance to move southward and slip into the Upper Midwest in early August, similar to that of the system that produced several damaging bowing segments over the Upper Midwest, Great Lakes and Northeast over the past several days.

What happened then and is forecast to happen in early August have very similar features, as seen below in this chart of the weather pattern on July 23.

On July 23, there was a low pressure system in the Upper Midwest with trailing cold front, with a ridge of high pressure extended from the Southeast out into the Plains. If we compare this map to the ECMWF forecast, it does become apparent that these systems are very similar. A key difference in any possible resulting thunderstorm track is the lack of a ridge in the Southeast. One was observed on July 23, which was the day of the derecho in the Ohio Valley. However, now, with the lack of a ridge, we could see the progression of possible storms more into the Ohio Valley. Also of potential is that the system could move east and the storms would deflect into the Northeast. Time will tell, and the models should align soon.

Andrew

Drought Worsens Across Nation; Outlook Miserable

The latest drought monitor update on July 24 cites an increasing and worsening drought across the nation, with Extreme to Exceptional drought conditions most prevalent across the Plains and Midwest.
With this latest update, the hope for help for agricultural products dims further, and it is likely that entire sectors of the agricultural business may be a total loss.
Now, we look from the short term corn crop concern to the question of 'How long will this last?' I can tell you that it will take months to regulate this deficit.

This map shows the precipitation needed for the drought to end. But, before we analyze it, there are some caveats. First and foremost, the needed precipitation must fall over a prolonged period of time. If it happens to fall all at once, only a small fraction of help will be delivered, while the rest of the rain will run off the dry ground and produce flash flooding.
The areas needing most precipitation (on the order of over 15 inches of rain) includes the Southern Plains into portions of the Midwest. This is typical of an El Nino pattern, with a possible expanse eastward and further deterioration of soil conditions.

I am predicting this drought to continue for months to come, into 2013. Considering we are entering an El Nino, I find the Plains and Midwest to be between a rock and a hard place, with El Ninos typically delivering below normal precipitation to the mentioned areas.
If you are a farmer based in the Midwest, I must say that the next 4-8 months (or beyond if the pattern holds) are looking miserable for agricultural crop harvests and/or plantings.

Andrew

Friday, July 27, 2012

Atmosphere May Be Showing El Nino Signs in Precipitation Placement

The latest GEM 144 hour accumulated precipitation forecasts displays a very El Nino-like pattern, with little precipitation in the Midwest and a lot of wet weather on the East Coast.

As is typical in El Ninos, precipitation is favored over the East Coast into the Gulf of Mexico coast, with little precipitation over the Ohio Valley and Midwest. The image above very well shows the pattern described, with a wet pattern holding out over the East Coast. But is the atmosphere showing an El Nino in other indices?

The Southern Oscillation Index, or SOI, is rapidly dropping, characterizing an El Nino pattern. El Ninos are detected when the SOI is below -8, and as shown above, the SOI is below -10.
BUT!
A look at the 30 day average of the SOI, used in the graph above, shows that the 30 day average has shot up to a value of positive 2. Positive values above 8 indicate a La Nina. This is fairly confusing for the atmosphere, because sea surface temperatures are positive, while the SOI is in fairly neutral territory. This will become interesting to monitor as we progress into the fall months to see if the atmosphere can sort itself out.

So while the precipitation appears to support an El Nino pattern, the SOI is in disagreement, and it will likely take a good month to see the SOI sort itself out.

Andrew

Thursday, July 26, 2012

Derecho Potential Video Briefing

Apologies for the bad sound quality, a nasty cold I have adds to the distortion thanks to the video itself.

Severe Storms Initiate in Northeast

There is a severe thunderstorm watch over parts of the Northeast and Ohio Valley, as strong to severe thunderstorms quickly get going in the mentioned regions.

It is very possible that this line could form more storms to the southwest, and these storms could produce a derecho based on the derecho composite values seen below.

This could become a very violent situation in a very short amount of time should storms form in the southern Ohio/West Virginia area. This entire situation will need a lot of monitoring for the rest of the day, and I will be closely watching storm development through the day.

Andrew

Wednesday, July 25, 2012

Moderate Risk Issued for Michigan

A short term moderate risk has been issued for Michigan as strong to severe thunderstorms fire in the region and move south.
Water vapor imagery clearly shows the sudden development of new strong thunderstorms, and the threat is expected to grow as the storms enter an area favorable for damaging winds.

Andrew

Significant Damaging Wind Possible Tomorrow in Northeast

There is the potential for significant damaging wind tomorrow in the Northeast, leading the Storm Prediction Center to include a moderate risk for much of the area I outlined in pink.

The latest NAM model is projecting strong to severe thunderstorms to fire along an advancing cold front in the Northeast and Ohio Valley tomorrow. This cold front appears to ignite a long stretch of several strong to severe thunderstorm clusters along the mentioned regions. 850mb winds will be pushing 35 knots, signaling the atmosphere's willingness to get something going, particularly severe thunderstorms. Additionally, as much as 4000 j/kg of instability may be present to support the storms, which appear to want to fire in the afternoon hours into evening.

This situation is being closely monitored at The Weather Centre, and a Storm Action Day (SAD) is going to be called tomorrow.

Andrew

Tuesday, July 24, 2012

Severe Weather Targets Great Lakes Tomorrow

I am watching an area of severe weather potential across the Great Lakes region, particularly over parts of the Northeast into the upper Western Great Lakes. Also of concern is the threat of overnight thunderstorms across the darker red region.

In the early hours of tomorrow, the 18z NAM model is projecting a cluster of showers and thunderstorms to develop across northern Minnesota and shift eastward in the midst of little instability but modest lifting. Of particular concern to this potential cluster will be how it reacts to what is forecast to be a strong cap over the region. It is a given that the lower level jet stream is nocturnal, and this is likely what will enhance storms to form over the area and keep them going in what would otherwise be an unfavorable environment for thunderstorms.

At this point, we are approaching late morning and the mesoscale convective system continues to show signs of continuing to move across the upper Midwest region, at this point now into far northern Wisconsin and the northern portion of Michigan. The NAM is progging the lower level jet stream to be in the 50-55 knot vicinity, enough to support strong to severe thunderstorms, even in the nighttime or late morning hours, when instability is traditionally not strong. I feel that the Lower Great Lakes may have to be on watch in this time as well, as the NAM is indicating a good 25-35 knot streak in the lower level jet may come to a point in the region.

Moving on into the wee hours of Thursday morning, the MCS makes an attempt to enter the Northeast, now once again holding its strength to the tune of possibly 60 knots of wind in the lower level jet stream. 3 hour precip forecasts, as shown above, are not as significant as they were on Wednesday morning's forecast, but remain significant enough to pose the question of severe weather potential. Notice the hints of blue in the western portions of the Lower Great Lakes. Further analysis of the 700mb winds does show over 30 knots of winds over that region, which would support some showers and storms, but not exactly on a severe level.

Here is the 1 hour precipitation forecast off the 21z Rapid Refresh model. It shows the bulk of the precipitation placed north of where the NAM is showing. This, in turn, would lead to a severe weather risk displaced farther to the north, should the low pressure system responsible make a move for this solution. This image is valid at about 9:00 AM CDT tomorrow and is long range for this short range model. However, it is indeed worth watching and will need closer monitoring into the morning hours tomorrow.

Andrew

Derecho May Form Soon

The derecho that has been in the realm of possibility appears to be on its way to forming, with the mesoscale convective system (MCS) now moving into the Ohio Valley and Mid Atlantic as shown below on radar. Derecho composite values, also shown below, illustrate the potential for a derecho to form in an area. As you can see, those values are elevated where the storms exist.

Andrew

Derecho Possible in Mid Atlantic Today

There has been a lot of interest over the potential for a derecho in the Ohio Valley and Mid Atlantic today, and after looking at the models, I believe that it is a possibility. However, the models have come in weak this morning. They still express a derecho-looking bowing segment to charge into the Ohio Valley and Mid Atlantic, but it looks weaker on this morning's runs than last night's models.
To the left, we see Northern Indiana's NWS office's WRF model. At roughly 1:00 PM CDT, this WRF is forecasting a bowing segment to hit the states of Kentucky and West Virginia. The 0z NAM, which had been portraying at least a moderate derecho, now appears to be seeing more of a cluster of showers and storms that could end up resembling that of a bowing segment. The general model consensus seems to be on the dim side as for derecho potential. But is that true after all?
The latest severe weather outlook for wind shows a 30% area for damaging winds in the areas being watched for the possible derecho. Considering the above image was for 1:00 PM CDT and the storms would likely strengthen as time goes on, personally, I do find it somewhat difficult to agree with the models. With the assistance of this Ring of Fire around a high pressure system, the upper winds aloft would seem to support more of a derecho solution panning out, especially with the lower level jet stream going through that area.

All in all, I personally see a derecho still on the table, but the models seem to be on the iffy side with it. We will see what happens this afternoon.

Andrew

Monday, July 23, 2012

Latest Model Forecast Highlights Derecho Concern

THIS JUST IN

The latest 0z NAM model forecast continues to highlight the concern of another derecho in the Ohio Valley and Mid Atlantic regions tomorrow, with this latest forecast giving the two Virginias and Kentucky the brunt of this complex.
The image above is valid at 4:00 PM CDT, and highlights 3 hour precipitation in millimeters. Based on the above image, we see a bowing segment placed in West Virginia and Kentucky putting out potentially high precipitation. With any bowing segment comes the risk of damaging winds, but with a derecho this danger is greatly increased.
A derecho is a long-lived wind storm spanning a large area, while a bowing segment involves a small, weaker bow in a much smaller scale region. Considering the strength and span of this bowing segment, as well as the distance it will have travelled (origins from Chicago, IL), I believe that this has the characteristics of a derecho, and would most likely prompt damaging wind potential.

I will issue a special morning post on this matter tomorrow morning with a full model update.

For the initial derecho post, click here.

Andrew

Derecho May Strike Ohio Valley Tomorrow

For the 9:55 PM CDT Update (7/23), CLICK HERE

There does appear to be potential for yet another derecho tomorrow into the Ohio Valley and Mid Atlantic regions, as the latest NAM model shows a strong bowing segment of storm cells storming through the Ohio Valley at around 4:00 PM CDT. With the potential for a second derecho, one begins to wonder, how does this happen? This summer, there has been a strong ridge of high pressure stationed over much of the Plains into other portions of the nation, and around this ridge is called the 'Ring of Fire' This Ring of Fire earns its name by being the hotspot for multiple complexes of showers and thunderstorms on an almost daily basis. This happens by a warm, moist and unstable air mass surging into an area. The Ring of Fire, which carries with it the Lower Level Jet stream, combines instability and wind shearing into the potential for potentially multiple complexes of showers and storms, also called a mesoscale convective system (MCS). This potential derecho situation looks to be part of this Ring of Fire. 
According to the latest 12z WRF run shown on the left, valid for tomorrow afternoon, there is also a derecho shown, but this one goes more into the Mid Atlanti than into the Ohio Valley. Either way, the potential remains for significant storms to fire tomorrow in the Ohio Valley and Mid Atlantic, and this could become a derecho. It will certainly have to be monitored.
Andrew 

Overnight Severe Weather Possible for the Midwest, Great Lakes

There is a slight risk of severe weather extending from the Northeast into the Midwest and Great Lakes.

Midwest
A frontal boundary will move through the region late in the day today, and may provoke some isolated thunderstorms. The concern rests overnight, however, with the nocturnal lower level jet stream amping up and providing a safe haven for strong clusters of showers and storms to develop. Given the strengthened lower level jet stream, wind shear in the midst of elevated instability will most likely give way to storms capable of damaging winds and hail. Due to the shearing, a tornado has potential to form as well, but this is not a big concern.

Northeast
Strong storms have developed in the Northeast and Ohio Valley and are expected to continue to develop and strengthen, with Round 2 possible overnight. Despite the loss of daytime heating, a disturbance with shearing will move into the area and promote severe weather overnight. Large hail and damaging winds are possible.

Andrew

Sunday, July 22, 2012

Over 110 Degree Temperatures Possible Tomorrow

The 12z NAM is showing temperatures reaching beyond 110 degrees tomorrow afternoon, temperatures that could seriously threaten the health of thousands. Big cities like Davenport, Iowa may bear the brunt, with Chicago, Illinois not in a horrible position, but still passing 100 degrees.

The question is concerning the reliability of this model. It does seem way overdone, and I believe that temperatures are about 10 degrees more than what it will turn out to be. Nonetheless, dangerous weather is likely tomorrow, including triple digit temperatures across the Midwest.

Andrew